Anti-epileptogenesis: Electrophysiology, diffusion tensor imaging and behavior in a genetic absence model

Abstract

The beneficial effects of chronic and early pharmacological treatment with ethosuximide on epileptogenesis were studied in a genetic absence epilepsy model comorbid for depression. It was also investigated whether there is a critical treatment period and treatment length. Cortical excitability in the form of electrical evoked potentials, but also to cortico-thalamo-cortical network activity (spike–wave discharges, SWD and afterdischarges), white matter changes representing extra cortico-thalamic functions and depressive-like behavior were investigated.WAG/Rij rats received either ethosuximide for 2months (post natal months 2–3 or 4–5), or ethosuximide for 4months (2–5) in their drinking water, while control rats drank plain water. EEG measurements were made during treatment, and 6days and 2months post treatment. Behavioral test were also done 6days post treatment. DTI was performed ex vivo post treatment.SWD were suppressed during treatment, and 6days and 2months post treatment in the 4month treated group, as well as the duration of AD elicited by cortical electrical stimulation 6days post treatment. Increased fractional anisotropy in corpus callosum and internal capsula on DTI was found, an increased P8 evoked potential amplitude and a decreased immobility in the forced swim test. Shorter treatments with ETX had no large effects on any parameter.Chronic ETX has widespread effects not only within but also outside the circuitry in which SWD are initiated and generated, including preventing epileptogenesis and reducing depressive-like symptoms. The treatment of patients before symptom onset might prevent many of the adverse consequences of chronic epilepsy.